Vacuum cleaners can include an agitator for agitating debris on a surface to be cleaned so that the debris is more easily ingested into the vacuum cleaner. In some cases, the agitator comprises a motor-driven brushroll that rotates within a base assembly or floor nozzle and is driven by a belt coupled with the motor. Vacuum cleaners with rotating agitators are often provided with a device for stopping agitator motion by disengaging the belt drive. Such belt drive disengaging devices allow the motor to remain on, but stops the agitator from rotating by physically moving or putting slack in the belt. This is useful when the vacuum cleaner is used for cleaning uncarpeted or bare floors, including hardwood, linoleum, tile, and tatami floors. Otherwise, the rotating agitator can generate air currents that push lightweight dust and debris away from the agitator so that they are not drawn through the suction nozzle and collected. A rotating agitator can also damage certain bare floors. It is also often desirable to disengage the belt drive when the vacuum cleaner is left stationary and used for above-the-floor cleaning, as even more robust floor coverings might be damaged by the rotating agitator.
One general type of belt disengager is a “belt tightener” or “belt tensioner.” In this type of agitator drive system, the drive belt is slack around a portion of the agitator, such as a drive pulley on the agitator, and a driven pulley or other driven member connected to the drive shaft of the motor, and thus the agitator will not rotate. To engage the belt, a belt tightener or tensioner is pressed against the belt to take up any slack, thereby causing the agitator to rotate.